This invention is related to the delivery of expandable devices commonly called "stents" within a body lumen such as an artery and the expansion of the stent therein to maintain the patency of the body lumen. The invention is particularly suitable for the delivery of stents after angioplasty procedures.
Percutaneous transluminal coronary angioplasty (PTCA) is now a widely practiced procedure for treating coronary artery disease. In a typical PTCA procedure, a dilatation catheter having an inflatable, relatively inelastic balloon on the distal end thereof is advanced through a patient's arterial system until the deflated balloon crosses an atherosclerotic lesion to be dilated. The balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g. up to 8 atmospheres or more) to compress the atherosclerotic plaque and to dilate the artery in the stenotic region. After dilation the balloon is then deflated so that the catheter can be removed. Due to the enlarged arterial passageway, increased blood flow results.
In typical PCTA procedures, a guiding catheter having a preformed distal end is first percutaneously introduced into the patient's arterial system and advanced until the distal tip of the catheter is disposed in the ostium of a coronary artery. A guidewire is slidably disposed within an inner lumen of a dilatation catheter and both are advanced through the guiding catheter to the distal end thereof. The guidewire is first advanced out of the distal tip of the guiding catheter into the patient's coronary anatomy until the distal end of the guidewire crosses the lesion to be dilated. The physician usually shapes the distal end of the guidewire to facilitate steering it through the patient's tortuous coronary arteries. Once the guidewire is in place, the dilatation catheter is then advanced out of the distal tip of the guiding catheter over the guidewire until the deflated balloon on the distal end of the dilatation catheter is positioned across the lesion. The balloon is inflated to a suitable pressure to dilate the stenosis, deflated, and then removed from the patient's vasculature.
For a more detailed description of the angioplasty procedures and the devices used in such procedures, reference is made to U.S. Pat. No. 4,332,254 (Lundquist); U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al); U.S. Pat. No. 4,569,347 (Frisbie); U.S. Pat. No. 4,571,240 (Samson et al); U.S. Pat. No. 4,616,652 (Simpson) and U.S. Pat. No. 4,748,982 (Horzewski et al) which are hereby incorporated in their entirety by reference thereto.
On occassion the inflation of the balloon during angioplasty causes a dissection in the arterial lining, e.g. the stenotic plaque or the arterial intima. When the balloon is deflated after such a dilation, blood can flow between the arterial wall and the dissected lining constricting the flow passage therein or causing a section of the dissected lining, commonly called a "flap," to be forced into the flow passageway thereby partially or completely blocking the blood flow through the artery.
Several methods have been proposed to resecure a dissected lining to the artery wall. For example, the dilatation catheter can be removed after the angioplasty procedure has been performed and replaced with a catheter having an expandable member at the distal end which allows for the perfusion of blood through the expandable member when expanded. In this method, the expanded member presses the dissected tissue lining against the arterial wall for an extended period until natural healing can result in the resecuring of the dissected lining to the arterial wall. Blood perfuses through the expanded member so that ischemic conditions are minimized or eliminated distal to the expanded member. However, these lining repair procedures usually require leaving the catheter with the expanded member in place for an extended period, e.g., several hours or more, in order to ensure that the lining has been properly resecured to the arterial lining. Suitable catheters for this purpose are disclosed in U.S. Pat. No. 4,790,315 and copending U.S. Pat. No. 4,498,537, U.S. patent application Ser. No. 07/404,815 filed Sep. 8, 1989, and U.S. patent application Ser. No. 07/404,818 filed Sep. 8, 1989, now U.S. Pat. No. 5,002,560, each of which are incorporated herein in their entirety by reference thereto.
Much development work has also been recently performed on the utilization of expandable stents in situations where long term expansion in an arterial or other bodily lumen is desired, such as in the instances described above. Expandable stents and their method of use are described in U.S. Pat. No. 3,868,956, (Alfidi et al); U.S. Pat. No. 4,512,338 (Balko et al); U.S. Pat. No. 4,553,545 (Maass et al); U.S. Pat. No. 4,655,771 (Wallsten); U.S. Pat. No. 4,733,665 (Palmaz); U.S. Pat. No. 4,739,762 (Palmaz); U.S. Pat. No. 4,762,128 (Rosenbluth), Japanese application 57-89859 published Jun. 4, 1982, and European Application 0183372 published Jun. 9, 1986 which are hereby incorporated herein by reference thereto. While this development work has been promising, no reliable and easily usable system has yet been developed which allows for the delivering an expandable stent to a desired location within a body lumen, particularly the coronary arteries, fixing the stent in an expanded condition within the bodily lumen and then removing the delivery system leaving the expanded stent in place. The present invention satisfies the need for such a stent delivery system.